Generally, it is recognized in the flexographic printing industry that printing runs are not of particularly lengthy duration. Typically, such runs usually last anywhere from a fraction of an hour to on the order of six hours. For this purpose, it is important for ink circulating systems to be capable of meeting the unique requirements of the industry.
As will be appreciated, ink circulating systems have usually included a tank containing ink of a selected color. Then, an immersion pump supporting a motor on a mounting plate is placed in the tank and a supply tube is connected to an outlet of the pump. In this manner, the pump is able to circulate ink to maintain a constant level and flow at the printing station.
In addition, ink circulating systems have other requirements including the ability to keep pigments, binders, solvents and additives evenly blended in suspension. This can be accomplished through constant conditioning and circulation which helps maintain uniform color and viscosity. Still further, since the tanks which hold the ink are conventionally covered by lids, the resulting closed system is practical for substantially retarding evaporation.
Unfortunately, cleanup and changeover of the pump has always been recognized as time consuming. It requires running a solvent through the pump for cleaning and entirely wiping off the external portions of the pump which have been submerged in ink; operations which normally take on the order of 20 to 30 minutes which is highly excessive in comparison with the duration of the typical run, e.g., a fraction of an hour to approximately six hours. However, due to the frequent changes in ink color, it is essential to undertake this cleanup process.
As will be appreciated, not only is the cleanup process time consuming, but it is also a dangerous undertaking. It is known, for instance, that the solvents used for this purpose can pose an environmental hazard as well as present the potential for explosions. For these reasons, it would be highly desirable to provide a disposable pump for such applications.
The present invention is directed to overcoming the foregoing problems and accomplishing the stated objects.